Again, Christian has an app for that (blog post).
You don't want to just ease the boom way out to let the hatch open fully - if the boom gibes, the vang will tear off your hatch cover.
But, I've been thinking about the pros and cons of reversing the hatch cover. Some clever hatches have hinges forward and aft to facilitate owner's preference, and to adjust to needed circumstances - no need to turn the frame. Maybe they weren't around when our boats were built.
My initial thought is that Ericson must have had very very good reasons for orienting the hatch as they did, so I needed to divine those reasons possible before deciding to follow Christian's lead. In addition to inherent laziness, here are my reasons for not reversing it (yet).
1. At anchor, you'll want it opening forward to catch any prevailing breeze
2. The vang impedes full opening, but my rope vang is attached to the base of the mast with a snap shackle, so it's easy to unclip it to allow as much hatch opening as i want (vang's not needed at anchor)
3. when sailing to weather in any sort of a seaway, you'll want that hatch completely closed - even if it opens afterwards, a lot of spray from the windward bow could go down below, coming in sideways to the open hatch.
Rigid vangs:
These are an excellent choice for racers because they give the main a bit of shape in very light conditions.
I know topping lift lines are a hassle (and if they break with the main down or while lowering it, the boom crashes to the deck (or into someone's head), but unless you have 100% faith in the solid vang, you'll likely keep a rope vang in pace anyway (?)
I think I've decided that I want my foredeck and cabin top hatches to open forwards - mainly for best breeze circulation at anchor. For that reason, I wouldn't want a rigid vang. (now I have a lot of virtual $ to spend on other more urgent upgrades - like an electric windlass...)